Blast furnace hot stove checkers



Feb. 15, 1966 W. G. SEACREST BLAST FURNACE HOT STOVE CHECKERS v Filed June 27, 1965 INVENTOR United States Patent 0.

3,235,240 BLAST FURNACE HOT STGVE CHECKERS William G. Seacrest, Limeport, Pa, assignor, by mesne assignments, to Bethlehem Steel Corporation, a corporation of Delaware Filed June 27, 1963, Ser. No. 290,999

2 Claims. (Cl. 26 3-51) This application is a continuation-in-part of a previous application, Serial No. 118,323 for Blast Furnace Hot Stove Checkers, filed June 20, 1961, now abandoned.

This invention relates to improvements in heat exchange checkerwork such as that employed in the regenerative chambers of furnaces used in the metallurgical, glass and similar industries, and is more particularly directed to an improved checker-brick arrangement for a blast furnace hot stove.

Blast furnace stoves are large cylindrical refractory lined. steel shells which preheat the blast before its admission, into the furnace through thetuyeres. Each stove consists of a combustion chamber, generally located at one side extending from top to bottom, and a checker Clean blastfurnace gas is conducted to the chamber. stove and burned at the bottom of the combustion chamber. The hot burning gases rise through the combustion chamber to the top of the stove and then reverse their flow and pass downwardly through the checker-bricks soaking them with heat; during this period the stove is on gas. When the cycle is reversed and the stove placed on blast, air passes through. the heated stove in a manner countercurrent to the passage of the hot gas; the blast passes upv through the heated checkerwork, reverses itself and passes.downward throughthe combustion chamber, then into the hot blast main, through the tuyeres and into the furnace.

Each blast furnace is served by a, plurality of hot stoves. When one is on blast furnishing heated air to the furnace, the other or others are being heated. In this manner a continuous supply of preheated air is always available to the furnace.

The efficiency of a hot stove is a function of many factors including time, temperatures, surface area of the brickwork available for contact with the heated gases, and the volume or mass. of heat absorbing refractory. The length of time a, stove is on heat determines the effective distance of heat penetration into the checker-bricks.

The refractory mass which is available for heat storage is.

the effective mass. The effective mass for design purposes, is that portion of. the. brick which is located perpendicularly behind an exposed heating surface. This effective mass and its ratio to the. exposed surface of the checkerbrick, which is the gate or valve through which the heat is transferred, is one of the important factors which determines the performance of a regenerator. The balance of weight between the effective and total weight influences a stoves storage capacity.

The optimum ratio between checker Weight and exposed surface that will determine the most effective stove performance will vary with the type of furnace operation expected, as influenced by the burden. Present burdens may require rapid and somewhat frequent swings to higher blast heats, whereas in the future with totally beneficiated burdens it is expected that practically steady straight line temperatures will be satisfactory.

Accordingly, it is an object of the present invention to provide a new improved checkerwork construction which presents a maximum effective brick mass while maintaining a strong and stable construction.

It is also an object to provide a checkerwork made up of a single brick design, simple in form and relatively inexpensive to manufacture.

est exposed surface, side faces 1 11-1, the

It is a further object to provide a checkerwork having unobstructed easily cleaned vertical flues throughout the construction.

The above and other objects of my invention will be more readily understood as the description proceeds.

FIGURE 1 is a fragmentary perspective view of one form of checkerwork structure built in accordance with my invention; and

FIGURE 2 is a plan view of the checkerwork of FIG- URE 1.

Referring to FIGURES l and 2, there is shown a checkerwork structure employing bricks 10 of generally elongated rectangular form in interlocked relation. Each brick has side faces 11 and end faces 12 and 13. At one edge of each side face 11 is a longitudinally extending lock rib or projecting portion 14 while at the opposite edge of each side face 11 is a longitudinally extending groove 15 of the same dimensions as rib 14 which engages the locking rib of an adjacent brick. Each groove 15 is bounded by a face 16 parallel to side face 11 and by' a face 17- perpendicular to the side face. Each locking rib 14. is bounded by face 18 parallel to side face 11 and face 19 and a portion of face 12, both perpendicular to the side face. The Width of face 18' is equal to one-half the thickness of the brick.

As shown. best in FIG. '2, the bricks are laid in rows designated: by the letters A, B, C and D, with the bricks ineach row. separated and the ends of the bricks in each row overlapping. This results in the formation ofa plurality of flues 20, each with four straight sides, with the width E- of each flue equal to the thickness F of'the bricks 1 The amount of overlap 21 is equal to one-half the thickness F of: the individual bricks. As can be seen, the adjacent rows of bricks are offset or staggered relative to each other, and the flue openings 20 in each roware staggered with respect to the flue openings in the next adjacent row, making a honeycomb or checkerboard arrangement.

As mentioned above, the length of time a stove is on gas limits the; effective distance of heat penetration into the checker-bricks. Thus, it is possible to determine, within limits, the depth ofheat penetration into a brick for any.- time, cycle used: in a particular hot stove operation. By making. the thickness F of-the checker-bricks approximately double. the depth of heat penetration during; the on gas period, and by restricting the lap width 21 to. oneahalf the brick thickness F, the total refractory mass of the checker-bricks is equally saturated with heat inproportion. to its perpendicular distance from the nearexposed p0rtionsof. endgfaces 12, locking rib faces 19, or end faces 13. And this is the essence of my invention. The shaded areas of bricks 22, 23, 24 and 25 of FIGURE 2 clearly illustrate how, during the on gas period, the heat progressively penetrates from an exposed heating surface into the body of the brick until there is complete soaking of the refractory. If the lap width 21 were to exceed one-half the brick thickness, there would be some volume of the brick, located at a greater perpendicular distance than the depth of heat penetration from the nearest exposed surface, which would not be soaked with a proportionate amount of heat. Any reduction in the lap width 21, to less than one-half of the brick thickness F, would not improve the proportionate heating of the refractory mass, as set forth above, and would decrease the stability of the checkerwork structure.

The result of my arrangement is a checkerwork provided, as shown in FIGURE 2, with flues 20, arranged in a plurality of rows A, B, C and D, the individual flues in each row being staggered with respect to the individual flues in the next adjacent rows, the distance separating the flues in each row (i.e., the brick thickness F) being twice the distance separating each two rows of flues (i.e., the overlap 21), and the width E of each flue 20 being equal to the thickness F of the brick separating the flues in each row.

With the exception of some half size bricks in the bottom and possibly the top courses, all of the bricks used in my checkerwork construction are of the same height. In starting the erection of the type described and illustrated in FIGURES 1 and 2, alternate rows of columns are started with bricks 26 cut to about one-half the height of the regular bricks. This provides a vertically stepped relation between the courses of alternate rows of columns as the bricks are superimposed one on top of another to the desired height. At the top of the checkerwork the short bricks 26 may be used in the alternate rows of columns in which they are not used as base bricks, in order that all the bricks of the top course have their upper surfaces in the same :horizontal plane. Thus, in the complete checker work structure, each joint between the abutting ends of superimposed bricks is guided and supported by corner engagement with four adajcent bricks.

A specific example of the checkerwork described and illustrated in FIGURES 1 and 2, is one in which the body of the brick is approximately 9" x 4 /2" x 2". The ribs 14 extend approximately A" out from the body of the brick and the groove faces 16 and the rib faces 18 are each 1" wide. The lap width 21, equal to the width of a groove face 16 or rib face 18, is 1", equal to onehalf the brick thickness. When these bricks are arranged in interlocking engagement in a checkerwork structure, vertical flues 20, which are 2 /2" x 2" in cross section, are formed.

The width 27 and thickness F of the bricks may be varied as desired. The governing criteria are that the lap width 21 is equal to one-half the brick thickness F, and that the width of flues 20 is equal to the brick thickness.

It will be observed from the above description and illustrations that a checker structure erected in accord- :ance with my instructions will possess the following advantages: a checkerwork having bricks of adequate thickness to prevent failure caused by chemical attack, accelerated by todays high temperature requirements; a structure formed of bricks with dimensions that may be varied to provide the desired relationship between brick mass and surface area; a structural arrangement simple in design while strong and stable in construction; a checkerwork construction having unobstructed easily cleaned vertical flues; and a checkerwork structure in which the refractory mass of the bricks is equally saturated with heat in proportion to its perpendicular distance from the nearest exposed brick surface.

Variations which normally occur in the dimensions of bricks will result in slight differences in the width of flues, the distance separating the rows of flues and the thickness of the bricks. Other shapes and patterns of brick may be provided to accomplish the results hereinabove described. It will be understood by those skilled in the art that modifications and variations may be made in the form and arrangement of the elements making up my improved checker structure without departing from the spirit of my invention. I do not, therefore, limit my invention to the specific form shown or to any particular size of brick, but claim as my invention all forms and arrangements coming within the scope of the following claims.

I claim:

1. checkerwork comprising a plurality of bricks, having end portions and rectangular body portions, formed into at least four contiguous rows of at least three bricks each with the ends of the bricks in each row overlapping the ends of two bricks in a contiguous row to form a plurality of rows of flues, the flues in each row being staggered with respect to the flues in the next adjacent row, the distance separating the flues in each row being approximately twice the distance separating adjacent rows of flues, and the width of each flue being approximately equal to the thickness of the bricks separating the flues in each row.

2. checkerwork comprising a plurality of bricks, having end portions and rectangular body portions, formed into at least four contiguous rows of at least three bricks each with the ends of the bricks in each row overlapping the ends of two bricks in a contiguous row to form a plurality of rows of flues, the flues in each row being staggered with respect to the flues in the next adjacent row, the distance separating the flues in each row being twice the distance separating adjacent rows of flues, and the width of each flue being equal to the thickness of the bricks separating the flues in each row.

References Cited by the Examiner UNITED STATES PATENTS 490,726 1/ 1893 Stevenson 26351 850,948 4/ 1907 Mohr 5046.3 X 1,167,081 1/1916 Kennedy 263-51 1,771,306 7/1930 Nelsom 263-51 1,848,242 3/ 1932 Claassen 263-51 OTHER REFERENCES Heat Transmission, William H. McAdams, published by McGraw-Hill Book Co., Inc., New York, NY. 1954, third edition, pages 1924 relied on.

WILLIAM F. ODEA, Acting Primary Examiner.

CHARLES SUKALO, Examiner. 

1. CHECKERWORK COMPRISING A PLURALITY OF BRICKS, HAVING END PORTIONS AND RECTANGULAR BODY PORTIONS, FORMED INTO AT LEAST FOUR CONTIGUOUS ROWS OF AT LEAST THREE BRICKS EACH WITH THE ENDS OF THE BRICKS IN EACH ROW OVERLAPPING THE ENDS OF TWO BRICKS IN A CONTIGUOUS ROW TO FORM A PLURALITY OF ROWS OF FLUES, THE FLUES IN EACH ROW BEING STAGGERED WITH RESPECT TO THE FLUES IN THE NEXT ADJACENT ROW, THE DISTANCE SEPARATING THE FLUES IN EACH ROW BEING APPROXIMATELY TWICE THE DISTANCE SEPARATING ADJACENT ROWS OF FLUES, AND THE WIDTH OF EACH FLUE BEING APPROXIMATELY EQUAL TO THE THICKNESS OF THE BRICKS SEPARATING THE FLUES IN EACH ROW. 